The longest outage in Facebook history was caused by a "server configuration change", according to the social media giant.
On Thursday, users worldwide were frustrated by an outage which caused Facebook, as well as WhatsApp and Instagram, to suffer issues.
All three services, which are owned by the same company, were down for more than eight hours for some users, and Facebook is now blaming a server configuration change.
"Yesterday, as a result of a server configuration change, many people had trouble accessing our apps and services," the company said in a Tweet.
"We've now resolved the issues and our systems are recovering. We're very sorry for the inconvenience and appreciate everyone's patience."
Users were confused by the outage and questioned if it may have been hacked or attacked.
But Facebook denied that was the reason.
"We're focused on working to resolve the issue as soon as possible, but can confirm that the issue is not related to a DDoS attack."